PROJECT SUMMARY/ABSTRACT Published work by the research team and data strongly suggest that prevalence rates and consequences of nonmedical prescription drug use (NMPDU) in older adults are increasing. That said, the specifics of NMPDU processes in this group are virtually unknown, with only three published studies that include older adults and examine NMPDU correlates. The long-term goal of the research team is to better understand nonmedical users and NMPDU processes (e.g., motives, diversion sources) across the lifespan, aiding intervention developers by identifying treatment targets and vulnerable subgroups of nonmedical users. In this application, using data from multiple years of the National Survey on Drug Use and Health (NSDUH), [the IMS National Prescription Audit and the NVSS Multiple Causes of Death files], the overall objectives are to: one, to better characterize older adult opioid, tranquilizer (primarily composed of benzodiazepines), [stimulant and sedative] NMPDU by establishing correlates, diversion sources, motives, and other key NMPDU indicators [and their relationships with NMPDU-related mortality]; two, to evaluate potential moderators in the NMPDU-correlate relationships, and factors (e.g., sex) associated with other NMPDU processes; and three, to establish latent classes of older adult nonmedical users of opioids, tranquilizers, [stimulants and sedatives]. Variable selection was guided by an adapted version of the Comprehensive Developmental Model of risk factors across different developmental periods, and all findings will be compared to those in younger cohorts, either directly in analyses or through comparison to previously published work. The rationale for this proposal is that better characterization of older adult NMPDU, including correlates, diversion sources, motives, and NMPDU subgroups will provide clearer targets for interventions to limit rates of NMPDU in older adults and the potential consequences of such nonmedical use. The contribution of this proposal will be significant because it will allow clinicians to identify older adult nonmedical users, particularly those who are most vulnerable to NMPDU-related consequences, and it will allow intervention developers to better craft robust prevention and treatment programs to limit and/or treat NMPDU in older adults. Furthermore, the research proposed here is innovative because it represents a significant departure from the current state of the field by applying accepted techniques and analyses, all previously utilized by the research team, to better characterize a vulnerable group of nonmedical users about whom very little is known, older adults. Other sources of innovation include the use of a nationally representative and large sample, inclusion of [multiple data sets and] a wide variety of NMPDU indicators to better characterize older adults engaged in NMPDU, and selection of analyses that examine sociodemographic and other developmentally-based moderators of key NMPDU processes. Rapid dissemination of the knowledge derived from this proposal has the potential to inform the development of maximally valid intervention options to prevent or reduce older adult NMPDU and its consequences, all of which is consistent with the mission of NIDA.